package cn.tedu.csmall.passport.felter;

import cn.tedu.csmall.passport.security.LoginPrincipal;
import cn.tedu.csmall.passport.web.JsonResult;
import cn.tedu.csmall.passport.web.ServiceCode;
import com.alibaba.fastjson.JSON;
import io.jsonwebtoken.*;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.security.authentication.UsernamePasswordAuthenticationToken;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.GrantedAuthority;
import org.springframework.security.core.authority.SimpleGrantedAuthority;
import org.springframework.security.core.context.SecurityContextHolder;
import org.springframework.stereotype.Component;
import org.springframework.util.StringUtils;
import org.springframework.web.filter.OncePerRequestFilter;

import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;

/**
 * <p>JWT过滤器</p>
 *
 * <p>此JWT的主要作用：</p>
 * <ul>
 *     <li>获取客户端携带的JWT，惯用做法是：客户端应该通过请求头中的Authorization属性来携带JWT</li>
 *     <li>解析客户端携带的JWT，并创建出Authentication对象，存入到SecurityContext中</li>
 * </ul>
 *
 * @author java@tedu.cn
 * @version 0.0.1
 */
@Slf4j
@Component
public class JwtAuthorizationFilter extends OncePerRequestFilter {

    @Value("${csmall.jwt.secret-key}")
    private String secretKey;

    public static final int JWT_MIN_LENGTH = 113;

    public JwtAuthorizationFilter(){
        log.debug("创建过滤器对象,JwtAuthorizationFilter");
    }

    @Override
    protected void doFilterInternal(HttpServletRequest request,
                                    HttpServletResponse response,
                                    FilterChain filterChain) throws ServletException, IOException {

        log.debug("JwtAuthorizationFilter开始执行过滤....");

        //清空Security上下文
        SecurityContextHolder.clearContext();

        //获取客户端携带的JWT
        String jwt = request.getHeader("Authorization");
        log.debug("获取客户端携带的JWT,{}",jwt);

        //检查是否获取到了基本有效的JWT
        if (!StringUtils.hasText(jwt) || jwt.length()<JWT_MIN_LENGTH){
            //无效的JWT放行,后边再处理它
            log.debug("获取到的JWT被视为无效,当前过滤器放行");
            filterChain.doFilter(request,response);
            return;
        }

        //尝试解析JWT
        log.debug("获取到的JWT被视为有效,准备解析JWT....");
        response.setContentType("application/json;charset=utf-8");
        Claims claims = null;
            try {
                claims = Jwts.parser()
                        .setSigningKey(secretKey)
                        .parseClaimsJws(jwt)
                        .getBody();
                //签名错误
            }catch (SignatureException e){
                log.debug("解析JWT是出现的SignatureException");

                String message = "非法访问! 滚!";
                JsonResult<Void> jsonResult = JsonResult.fail(ServiceCode.ERR_JWT_SIGNATURE,message);
                String jsonString  = JSON.toJSONString(jsonResult);

                PrintWriter writer = response.getWriter();
                writer.println(jsonString);
                return;
                //数据格式错误
            }catch (MalformedJwtException e){
                log.debug("解析JWT是出现的MalformedJwtException");

                String message = "非法访问! 滚!";
                JsonResult<Void> jsonResult = JsonResult.fail(ServiceCode.ERR_JWT_MALFORMED,message);
                String jsonString  = JSON.toJSONString(jsonResult);

                PrintWriter writer = response.getWriter();
                writer.println(jsonString);
                return;
                //签名过期

            }catch (ExpiredJwtException e){
                log.debug("解析JWT是出现的ExpiredJwtException");

                String message = "登录信息已过期,请重新登录";
                JsonResult<Void> jsonResult = JsonResult.fail(ServiceCode.ERR_JWT_EXPIRED,message);
                String jsonString  = JSON.toJSONString(jsonResult);

                PrintWriter writer = response.getWriter();
                writer.println(jsonString);
                return;
                //
            }catch (Throwable e){
                log.debug("解析JWT时出现Throwable，需要开发人员在JWT过滤器补充对异常的处理");
                e.printStackTrace();

                String message = "滚去解决问题!";
                PrintWriter writer = response.getWriter();
                writer.println(message);
                return;
            }

        //获取JWT中的管理员信息
        String username = claims.get("username",String.class);
        Long id =claims.get("id",Long.class);
        String authoritiesJsonString = claims.get("authoritiesJsonString", String.class);
        log.debug("从JWT中获取id：{}", id);
        log.debug("从JWT中获取username：{}", username);
        log.debug("从JWT中获取authoritiesJsonString：{}", authoritiesJsonString);
        //处理权限信息
        List<SimpleGrantedAuthority> authorities =
                JSON.parseArray(authoritiesJsonString, SimpleGrantedAuthority.class);

        //创建Authentication
        LoginPrincipal loginPrincipal = new LoginPrincipal(id,username);
        Authentication authentication = new UsernamePasswordAuthenticationToken(
                loginPrincipal,null,authorities
        );

        // 将Authentication对象存入到SecurityContext
        log.debug("向SecurityContext中存入认证信息：{}", authentication);
        SecurityContextHolder.getContext().setAuthentication(authentication);

        //放行
        filterChain.doFilter(request,response);
    }
}
